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Genealogical and population viability analysis of a conservation nucleus of Brazilian Bergamasca sheep

Published online by Cambridge University Press:  10 June 2014

H. Carneiro ,
S.R. Paiva ,
H. Louvandini ,
R.M. Miranda  and
C. McManus
H. Carneiro
Affiliation:
Faculdade de Agronomia e Medicina Veterinária, Campus Universitário Darcy Ribeiro, Universidade de Brasília, Brasília, DF 70910-900, Brazil
S.R. Paiva
Affiliation:
EMBRAPA Recursos Genéticos e Biotecnologia, Parque Estação Biológica, Avenida W5 Norte (Final), Brasília, DF 70770-900, Brazil
H. Louvandini
Affiliation:
Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, SP, CEP 13416-000, Brazil
R.M. Miranda
Affiliation:
Departamento de Zootecnia, Universidade Federal de Rio Grande do Sul, Av. Bento Gonçalves, 7712, Porto Alegre, RS, CEP 91540-000, Brazil
C. McManus*
Affiliation:
Faculdade de Agronomia e Medicina Veterinária, Campus Universitário Darcy Ribeiro, Universidade de Brasília, Brasília, DF 70910-900, Brazil Departamento de Zootecnia, Universidade Federal de Rio Grande do Sul, Av. Bento Gonçalves, 7712, Porto Alegre, RS, CEP 91540-000, Brazil
*
Correspondence to: C. McManus, Faculdade de Agronomia e Medicina Veterinária, Campus Universitário Darcy Ribeiro, Brasília – DF 70919-900, Brazil. email: [email protected]
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Summary

A genealogical and a viability analysis was carried out on the 1559 available registers for the Conservation Nucleus of Brazilian Bergamasca sheep of the University of Brasilia farm in Brazil using the ENDOG and the Vortex programs. To run the ENDOG it was used the registered data and for the Vortex it was used information obtained by a questionnaire answered by the curators of the herds. Of the animals registered, 767 had known parents, with significantly more dams known at each generation. The number of pedigrees known has increased over the generations, with higher registration of parents of sires than dams. The Computed Mean Inbreeding calculated by ENDOG was 0.29 percent and mean average relatedness was 1.52 percent. Mean Generation interval was 3.71 years with this values being lower for sires than dams. The population probability of extinction, calculated by Vortex was 17 percent and the average time to extinction was 59 years. Forty-two additional scenarios were created to determine which factors most threaten these populations which were frequency of catastrophes, lack of animal entrance and adult and lamb mortalities, especially adult female mortality. These results indicate that future breeding plans should include exchange of sires between farms to maintain low inbreeding levels and increase genetic variability and upgrade the management to control the mortality rates of animals.

Résumé

Une analyse généalogique et de viabilité a été réalisée avec les 1559 enregistrements disponibles au Centre de Conservation de la race ovine Bergamasca Brésilienne de l'Université de Brasilia (Brésil), en utilisant les logiciels ENDOG et Vortex. Les données des enregistrements ont été utilisées pour travailler avec le logiciel ENDOG alors que l'information traitée par le logiciel Vortex avait été obtenue au moyen d'un questionnaire auquel ont répondu les personnes prenant soin des troupeaux. Pour 767 des animaux enregistrés, les parents étaient connus, avec le nombre de femelles connues étant significativement plus élevé à chaque génération. Le nombre de généalogies connues a augmenté au fil des générations, grâce à un enregistrement plus fréquent des parents des mâles. La Consanguinité Moyenne a été estimée par ENDOG à 0,29 pour cent alors que la Parenté Moyenne a été de 1,52 pour cent. L'Intervalle Générationnel Moyen a été de 3,71 ans, avec l'intervalle étant plus court chez les mâles que chez les femelles. La probabilité d'extinction de la population a été de 17 pour cent d'après Vortex et le temps moyen d'extinction a été de 59 ans. Quarante-deux scénarios additionnels ont été créés pour déterminer quels sont les facteurs menaçant le plus ces populations. Ceux-ci ont été: la fréquence de catastrophes, le manque de renouvellement des animaux et la mortalité des adultes et des agneaux, notamment la mortalité des femelles adultes. Ces résultats indiquent que les futurs plans de sélection devraient envisager l'échange de mâles entre les fermes afin de maintenir bas les niveaux de consanguinité et d'accroître la variabilité génétique. Il faudrait, de même, améliorer la gestion des exploitations dans le but de contrôler le taux de mortalité des animaux.

Resumen

Se realizó un análisis genealógico y de viabilidad con los 1559 registros disponibles en el Núcleo de Conservación de la raza ovina Bergamasca Brasileña, de la Universidad de Brasilia (Brasil), usando los programas ENDOG y Vortex. En el programa ENDOG se trabajó con los datos de los registros mientras que en el programa Vortex se usó la información obtenida mediante un cuestionario al que respondieron los encargados del cuidado de los rebaños. De los animales inscritos, se conocían los progenitores de 767, con un número significativamente mayor de hembras conocidas en cada generación. El número de genealogías conocidas ha aumentado a lo largo de las generaciones, gracias a un mayor registro de los progenitores de los machos. La Consanguinidad Media calculada por ENDOG fue de 0,29 por ciento mientras que el Parentesco Medio fue de 1,52 por ciento. El Intervalo Generacional Medio fue de 3,71 años, siendo este dato menor para los machos que para las hembras. La probabilidad de extinción de la población, calculada por Vortex, fue del 17 por ciento y el tiempo medio hasta la extinción de 59 años. Se recrearon 42 escenarios adicionales para determinar cuáles son los factores que, en mayor medida, amenazan a estas poblaciones. Éstos resultaron ser: la frecuencia de catástrofes, la falta de reposición de los animales y la mortalidad de los adultos y de los corderos, en especial la mortalidad de las hembras adultas. Estos resultados indican que los futuros planes de selección deberían contemplar el intercambio de machos entre las granjas para mantener bajos los niveles de consanguinidad e incrementar la variabilidad genética. Asimismo, se debería mejorar el manejo de las explotaciones para controlar las tasas de mortalidad de los animales.

Keywords

average relatednessinbreedingpopulation modellingVortexWright statisticsconsanguinitémodélisation populationnelleparenté moyennestatistiques de WrightVortexconsanguinidadestadísticos de Wrightmodelización poblacionalparentesco medioVortex
Type
Research Article
Information
Animal Genetic Resources/Resources génétiques animales/Recursos genéticos animales , Volume 54 , June 2014 , pp. 103 - 113
Copyright
Copyright © Food and Agriculture Organization of the United Nations 2014 

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